This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to identify peptides presented by the diabetogenic MHC class II molecule I-Ag7 from NOD mice. Studies will use both NOD mice and cell lines derived from insulinomas. The study will extend to cover the effect of loading, posttranslational modification, and challenge by foreign peptides and proteins. Mass spectrometry will be used to sequence and catalog these peptides and the development of techniques to improve sensitivity and analysis will be pursued.